The distribution variation and key influencing factors of soil organic carbon of natural deciduous broadleaf forests along the latitudinal gradient

Soil organic carbon plays a key role in soil carbon stock in response to global climate changes. Forests are considered to be an important resource in contributing to mitigating the carbon cycling. Therefore, forest soils should be paid more attention in exploring soil organic carbon on a regional scale. The aim of this study is to explore the variation trend of soil organic carbon content and environmental impact in natural deciduous broadleaf forests along a north-south latitudinal gradient in China. Soil organic carbon showed a significantly (P < 0.05) decreasing trend with the latitude increasing, similar observation to total nitrogen. Partial Pearson correlation analysis indicated that total nitrogen was the most positively (R = 0.91) and significantly (P < 0.05) correlated with soil organic carbon, which indicated close coupling between carbon and nitrogen in soil. The climate, soil pH and plants were also the key factors in influencing the distribution of soil organic carbon.